Linking the health utilities index to National Medical Expenditure Survey data

Measures of health-related quality of life (HR-QOL) are becoming increasingly important in assessing the effects of chronic illness and healthcare interventions designed to treat them. Obtaining measures of HR-QOL for a nationally representative sample of individuals would enhance understanding of health status in the US, and promote further study of the economic causes and effects of health status. This study reports on our efforts to link a prominent HR-QOL scale, the Health Utilities Index Mark I (HUI), to the National Medical Expenditure Survey (NMES). Six distinct algorithms were constructed for linking the HUI to NMES. These alternative linkage algorithms yielded HUI measures that were highly intercorrelated (p = 93 to 99%). Multivariate regression analyses performed to predict variations in HR-QOL revealed that the HUI exhibited good predictive validity--the HUI demonstrated lower quality of life for a variety of chronic illnesses, and wealthier individuals and better educated individuals had a higher quality of life. In contrast to some previous HR-QOL research, the present analysis demonstrates that: (i) cancer is negatively and significantly related to quality of life; and (ii) smoking is negatively and significantly related to quality of life. Overall, the results suggest that the HUI linkages to NMES provide reliable and valid measures of quality of life. As such, items from the NMES can be grouped and linked in such a way as to obtain health state utility values. These values should be of use to those who wish to understand the global health of the US population for policy-making efforts.